Scalable Video Coding (SVC) has many advantages over classical Advanced Video Coding (AVC) (see, e.g., ITU-T Recommendation H.264 Amendment 3: “Advanced video coding for generic audiovisual services: Scalable Video Coding”). Scalability in SVC can apply to the temporal, spatial and quality (signal-to-noise ratio) domains. An SVC stream usually comprises one base layer and one or more enhancement layers. The base layer stream can be independently decoded but any enhancement layers can only be decoded together with the base layer and other dependent enhancement layers.
An advantage of SVC encoding is that the different layers can be transmitted in different IP streams and thus can be protected against transmission errors using different methods. For example, the base layer is more important than the enhancement layers and thus may receive greater protection. On the other hand, due to bandwidth limitations, enhancement layers are usually less well protected than the base layer, thereby making packet loss in an enhancement layer more likely than packet loss in the base layer.
When there is packet loss in an enhancement layer, the corresponding pictures in that layer and in the enhancement layers up to the target layer (the highest level layer needed to provide a target resolution), cannot be decoded. Traditional error concealment methods usually replace a lost picture by duplicating the picture of the previous frame or by interpolating several good neighboring frames. These methods usually render poor picture quality when the differences between the neighboring frames are large, such as in the case of a scene change in the lost frame.